The field of the invention is that of micro-instrumentation, that is, articulating, hand-held, instruments used in micro-surgery, electronic micro-assembly and like applications, for grasping, cutting, punching out, probing and the like. The instruments can comprise scissor-handle actuators, so-called cigar handle linear or rotary activators, or other actuators, with push or pull force application design modes.
The invention is particularly advantageous for endoscopic, or minimally invasive, surgery, but is also advantageous in other applications for micro-instrumentation.
Prior art endoscopic devices have included the traditional scissor-like linkage shown in FIG. 1, in which a drive member 2, linked to the ends of a scissor-like configuration of jaws 3 and 4 on a pivot mounted at the distal end of a tube 1, is pulled to close the jaws. This traditional arrangement suffers from the disadvantage of using four pivots, typically pins, which are subjected to significant shearing force, particularly where the linkage portion is short compared to the jaws.
An improvement upon these traditional devices was disclosed in U.S. Pat. No. 5,152,790 to Honkanen et al. and U.S. Pat. No. 5,219,357 to Honkanen et al. One feature of those inventions is the use of one or two jaws rotatably mounted on a pivot, each jaw 23 with a recess 231 off center to accommodate and absorbs force from the distal end of an actuating link 24 minimize the width of the structure that pushes the jaw closed around the pivot. This relieves the shear force on a retaining pin 241 that positions the distal end of the actuating link and is used to rotate the jaw open. FIG. 2 hereto shows a two-jaw configuration (only one jaw shown) disclosed in the second mentioned Honkanen et al. patent where one linkage member is used for each jaw and a common drive shaft 22, terminating at its distal end in a "T" 221, by a one-quarter turn, engages channels 242 within the linkage members 24 to push or pull the linkage members to respectively close or open the jaws.
Although the disclosed device has advantages in strength and form factor over the traditional endoscopic tool, it did not fully meet some of the new demands of medical procedure, which include requirements of cleanliness.